Children's charity NCH surveyed 770 youngsters and found 14% of 11- to 19-year-olds had been threatened or harassed using text messages.

Bullies had used images taken with mobile phone cameras to intimidate or embarrass one in 10 young people.

This included singling out overweight or spotty youngsters and recording and sharing acts of playground violence.

The findings follow reports of so-called "happy slapping" attacks - where assaults on children and adults are recorded on mobile phones and sent via video messaging.

'Intimidated'

John Carr, the NCH's new technology adviser, said: "For a child or teenager being bullied by mobile phone, it can be terrifying and feel like there is no escape.

"This new research reveals the massive scale of mobile bullying and shows how camera phones are being used by bullies to frighten and intimidate their victims."

Some 26% of digital bullying victims did not know who their tormentor was, the survey found.

Mr Carr said: "This extremely worrying phenomenon highlights the urgent need to tackle mobile bullying before it ruins more lives."

More than one in 10 respondents to the survey of 770 youngsters, carried out jointly with Tesco Mobile, said they had bullied others via text message, with half of all incidents happening within schools.

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But in terms of the proportion of children affected, the problem would not appear to be getting worse. A survey three years ago from the NCH claimed that one in four youngsters had been threatened via a mobile phone or computer.

'Traditional' bullying

A Department for Education and Skills spokesman said bullying in any form is unacceptable.

He said: "Every school must have an active anti-bullying policy - every adult in that school has a responsibility to tackle bullying, every parent has a responsibility to support their child and their school."

Anti-bullying charity Bullying Online warned that intimidation by mobile phone or internet was usually only a small part of the problem.

John Carnell, the charity's founder, said: "If a child is being bullied, they will most likely be being bullied in the traditional ways as well - physical assaults, teasing and so on."

He said the real problem was bullying, not technology.

The NCH report found that 5% of young people had been bullied in internet chatrooms and 4% via e-mail. And the charity is launching an interactive website - www.stoptextbully.com - to give advice and support.

The problem of mobile phone bullying has become apparent alongside the growth of mobile phone ownership among young people.

Bullying Online was warning of text message bullying more than five years ago.

And in a clampdown on bullying in 2002, the Department for Education warned that children who used mobile phone text messages to intimidate other children could be expelled from school.

Do you know anyone who has experienced bullying via mobile phone or the internet? Contact us using the form at the bottom of this page.

Here are some of your responses.

Mobile phones are not the problem. The real issue lies in a lack of respect for other people. Ban phones, ban hoodies, ban pencil cases, it won't make any difference, these people will find new ways, means and methods to terrorise their peers.
Mark Brier, Manchester, UK

My son was bullied over the internet and on his mobile and my niece was also bullied on her mobile phone. A lot of kids think it's a good laugh and so do their parents. Not sure how you tackle the problem when the bullies are as sick as their parents. As for bullying at school - come on, the teachers can't stop the kids from swearing at them let alone stopping them from bullying other kids.
Heather, North West UK

Why is this called bullying? Anyone can turn off a phone or delete a text message. We have a problem that whereas one child will regard something as a harmless joke, another will go snivelling to teachers and parents. I remember being taught: "Sticks and stones may break your bones but names will never hurt you."
Paul, United Kingdom

It is possible to buy a phone without a camera on it - that way you don't receive any pictures. If anyone is being bullied, no matter how scared you are, you have to tell somebody before it gets out of hand. It will probably be the scariest thing you've ever done, but it could save your life. I was bullied every single day from the age of 10 to 19. It scars you for life if you keep it to yourself. I am now 31 and have only just got my confidence back thanks to some very good friends. If I knew then what I know now, I would have told somebody and saved myself a lot of hurt.
Angie, UK

Just ban them from schools altogether. They aren't needed so why allow them there. It appears in this case they are being used as a weapon. You wouldn't allow children to carry a baseball bat in their bag - even if it was only for use at break!
Carl Parsons, England

One way of reducing this problem is for areas such as schools, hospitals and cinemas to be allowed to put in phone transmitter blockers. Of course, phone companies wont like it.
Adrian, UK

One way of stopping this would be to stop withheld numbers. The bullies usually are not brave enough to leave their phone number.
Yosef, UK

The solution is to obtain recordings from the mobile phone company and, for those who have offensive texts or image recordings, to have their phone shutdown with a lifetime ban from owning another mobile.
Rob Bluck, Birmingham UK

We have had instances of inappropriate use of camera phones in the comprehensive school where I work. These devices are an absolute menace. Is there no way of neutralising them during the school day? We can't collect them all from over 1,000 pupils as they arrive in the morning. Teachers can't be sure they are turned off. Sooner or later a child will take an unsolicited picture of a teacher or another pupil and put it on to the web. This would certainly be bullying and an unwanted invasion of privacy which might well attract the attention of the lawyers. Perhaps there could be advantageous pricing of calls outside peak times - school opening hours in our case. This is probably quite difficult - then again, we sent a man to the moon 35 years ago and are planning a system to "tag" every vehicle on British roads in the next decade.
Chris, Lincoln, United Kingdom